Modelling of fluid structure interactions in submerged flexible membranes for the Bombora wave energy converter

摘要

This paper presents a coupled Computational Fluid Dynamicsand Fluid Structure Interaction model of the Bombora wave energyconverter. The model consists of three components – themembrane, the power take off system (PTO), and the ocean –which are solved together to capture the device behaviour. Theocean (and waves) are solved using the volume-of-fluid method,the membrane is solved using a simplified Finite Element (FE)model, and the PTO is solved using a thermodynamic model ofthe ducting and turbine. OpenFOAM is used for the VoF models,extended by the waves2Foam toolbox. The membrane andPTO models are implemented from scratch as separate customlibraries, using OpenFOAM’s base classes.Comparison between the fully coupled inflation model and theuncoupled inflation model indicates that, as expected, the dynamiceffects of the water cannot be ignored. It is expected thata combination of increased damping, and additional membranemass may be able to account for a large part of the fluid loading.As a consequence of the different response times for eachcomponent of the model simulation run-times are excessive, andthese simulations seek to quantify the certainty of some of theassumptions in the simplified models. However, future workwill investigate alternative methods for coupling these modelstogether.